Why line graph not plotting completely in extjs?

I have done application using Extjs 4.1. In this app implemented many charts working nicely. But one issue is facing in line chart, not able resolve it. Line chart is not plotting completely till end of the month.Json contains complete month data, no doubt at all. On mouse hover on line graph data will shows particular month and date. For more reference have attached two images (Dec-Jan and Dec-Feb). I have tried lot but not able to resolve. Find the image and code let me know. From where i am getting this issue. How can i resolve? Great appreciated. Thank you.Code Here:

Hi, Thank you for your reply. Already my team member is tried in 4.2.1 but still have the same issue. Find the link . http://www.sencha.com/forum/showthre...rking-properly . still have bug in Extjs 4.2.1. This issue very headache not able to resolve. customers are pointing to this issue only . How to resolve this issue ?. Great appreciated. Thank you.